Inner tank bracing question

My boyfriend and i are currently in the process of building a 1200mm x 480mm x 500mm (LxWxH). We bought all of the glass and realized that the inside bracing width is 8cm to short. If i space it evenly i would have a 4cm gap each side between the length wise bracing. Would this cause a weakness on the inside of the tank? Would it be better to get a new piece cut that is the right size or can i use the current brace with the gaps?

You could omit using the side bracing if you wanted to. It won't effect the structural integrity of that size tank. The fact that you have gone 10mm all round weighs greatly in your favour.

My 1.5m Rimless threadLeslies 1.8Treat the earth well. it was not given to you by your parents,it was loaned to you by your children. Indian proverb.Before implementing somebody's advice, have a look at their tank thread it will give you a good indication of where you will end up following their advice! Les Hempel.​

That shorter pieces should be fine at the bottom.
Would just provide bigger area to hold the front and back panels in place. Instead of just 10mm silicone, it would now be 20mm. The 40mm gaps would be insignificant.

Only negative part might be the front view. But with cabinet coming up in front of the tank high enough to hide the bottom panels, it would not be an issue.